Method and apparatus for dehydrating liquid products



April 21, 1942. J. M. HALL 1 2,280,073

" METHOD AND APPARATUS FOR DEHYDRATING LIQUID PRODUCTS Fi led Ma -15,1959 4 2 Sheets-Sheet 1 I} v' y 78 :I i j 7% 4s g ii April 21, 1942. J.M.HALL; 2,280,073 METHOD AND APPARATUS FOR DEHY DRATI NG LIQUID PRODUCTS I Filed May 15, 1959 2 Sheets-Sheet 2 'gj a the fan and associatedPatented Apr. 21 1942 I Ma'r'uon ES PAT AND APPARATUS FOR ING LI QUIDPRODUCTS v Joseph M. Hall, Chicago, Ill.

nnurnaa'r- Application May 15, 1939, Serial No. 273,641 (Cl. 159-4) v 6Glaims. This invention relates to concentration and dehydration ofliquid products.

. One of the objects of the invention is the provision of a. new andimproved concentrating and dehydratlngapparatus having novel means fordesiccating liquid products of various types.

Another object of the invention is the provision of a new and improvedsystem forconcentrating and dehydrating liquid products that employs aminimum number of vacuum pans or chambers.

A further object of the invention is the provision of a new and improvedmethod and apparatus for concentrating and dehydrating liquid tlnuousprocess.

products on a large production'scale in a conused for concentratingother liquid products that may be subjected to a similar treatment.

In the treatment of milk and other food products, it is necessary, andis the custom at the present time with most of thelarger producers, tothoroughly clean and sterilize each portion of the apparatus thatcontacts the milk at least once each 24 hours in order to insure againstcontamination and the growth of injurious bacteria. One of the principalobjects of the present invention is the construction of an apparatusthat may be easily, quickly and inexpensively cleaned. By employinglarge evaporating cham- A still further object of the invention is theprovision of a new and improved apparatus for concentrating anddesiccating liquid products having a minimum number of parts and those.

parts so constructed that they may be washed or cleansed with a minimumof labor and exense Another object of the invention is the. provision ofa new and improved apparatus for concentrating and desiccating liquidproducts that is inexpensive to manufacture, simple in construction,easily assembled, that maybe operated at a minimum of expense, and onethat employs air as the dehydrating medium.

Other and further objects and advantages of the invention will appearfrom the following de- I scription, taken in connection with theaccompanying drawings, in which- Figs. 1 and 1a, taken together, showaside elevation of 'the apparatus shown diagrammatically and with partsinflsection and parts broken away: h

Fig. 2 is a top plan view of the upper portion of" the dehydrator ordesiccator Fig. 3 is a side elevation of the dryerand air separatortaken 90 from that shown in i Fig. {is a top plan viewof Fig. 3; Fig; 5is a top plan view of of the evaporator;.and

Fig. 6 is a perspective view of a portion of parts; with parts brokenaway. i l

In order to disclose one embodiment'of'the invention, the structure willbe described as an apparatus for, and system of, evaporating anddesiccatlng milk and like products. It is understood, however, that thisis by way of example only and that the system or apparatus may be 55 theupper portion bers of the centrifugal separator type instead of thetubular vacuum chambers usually employed, the cleaning operation isimmensely simplified and the parts readily and easily cleansed.

In the apparatus herein disclosed, the liquid product to-be treated ismoved in one direction through the apparatus and the evaporating ordehydrating fluid is moved through the apparatus in a closed circuit inthe opposite direction.

' Referring now to the drawings, Figs. 1 and 1a,

taken together show, more or less diagrammatically, one embodiment ofthe'invention. The entire evaporating and desiccating apparatus isdesignated by the reference character l0 and the apparatus for handlingthe liquid product comprises a reservoir II for containing the liquidproduct'to be dehydrated, a vacuum pan or chamber l2, a separator IS, avacuum pump I 4 and a condenser l5 for partially evaporating themoisture from the liquid. This apparatus also comprises an evaporatorchamber I6 for concentrating the product, a desiccator chamber IT fordehydrating or desiccating the product and a cooler l8 and air separatorIQ for cooling and collecting the powder.

The heating medium or fluid is air and the mechanism for handling theair comprises an air conduit 20, a fan or blower 2| and an "air conduit.22 within which is located the fu'rnacebr heater 23. The conduit 22delivers heated air into the dehydrating or desiccating chamber IL. Themechanism also comprises a return conduit 24 and a furnace or heater 25for heating the air in theconduit 24 The conduit 2 delivers the heatedair into the evaporating chamber 16. An

air passage 31 conducts the air from the evap- EINT OFFICE f in itslower end forming Y28 and 291 liquid product carried over a of theliquid product. an extension to which a the headers 3| and 32,respectively. Suitable tubes 33 have their upper and lower ends rigidlysecured in the partitions These tubular members are in communicationwiththe headers 3| and 32 and milk orother'liquid'product from the reservoirH is adapted to fill the lower header 32- and partially fill the tubes33. A pipe 30 between the reservoir valve 30a controls the flow of theliquid product.

The level of the liquid products in the tubes may be above that in thereservoir ll because of the partial vacuum in the header 3'! and tubescaused to rise therein by atmospheric pressure. The header 3| is incommunication with the separator I3 through a conduit 34 and a deflector35 is provided on the inner end of thhe conduit 34 for directing the'from the vacuum chamber by the vapor generated therein downwardly intothe lower portion of the separator l3. A suitablegauge'36 may be mountedon the-conduit 34 for indicating the pressure in the conduit, header andseparator. The outer casing 21 of the vacuum chamber l2 forms a jacketabout the tubes 33 and this casing is in com- 33. The liquid will be'munication with an air passage or conduit 31 which conducts heated airfrom'the evaporator l6, as will presently appear.

The separator l3 comprises an upper enlarged section 38 and a lowerreduced section 39, the lower portion of which contains more or less Theuppersection 38 has this tube is in' communication with the jacket ofthe steam condenser l which in turn is in comv munication with thevacuum pump l4 through a passage 42. The condenser l5 has a coil 43therein for conducting cool water to-and from the condenser forcondensing the vapor that is withdrawn from the liquid product while inthe vacuum pan or chamber l2 and separator l3. The water condensed maybe discharged from the vacuum pumps into the waste or it may be 7utilized in other portions of the plant.

The header 32 is provided with an outlet passage 44 which is also 7lower section-39 of in communication with the the separator by a conduit45. The heated air entering the jacket of the vacuum chamber l2 throughthe passage 31 will impart its heat to the millg contained in the tubes33 and since the milk in 'the tubes is under a partial vacuum, the milkwill be boiled and the moisture, in the form of vapor, withdrawn by thevacuum pump H. The evaporation of the moisture in the milk will in turnreduce, the tem-' perature of the air in the jacket 21- below itssaturation point. As a consequence, a certain amount of the moisture inthe air willbe precipitated and the liquid may passoutward through thetube 46 either as a-'waste or it may be utilized for other purposesabout the plant.

The milk or liquid product in the passage 44 is transferred by thepump'41 to a sprayhead 48 in the evaporator Hithrough the pipe 40. The

spray head 48, Figs. la and 6, is suspended byaspindle 49 axially of theevaporator chamber l6. The spindle 49 is-provided with suitable journalsand'isadapted to be rotated in anyconventional manner'as by means of themotor 5|; The armature shaft of the motor constitutes aspindle whichissurrounded by a tapered cone-shaped shield 52 that positions the same.49 is hollow" and is adapted to convey tube 4| is attached and Thespindle the liquid product to The spray head 48 comprises a plurality ofarms 53 which extend radially outwardly in a substantially horizontalplane. These arms are hollow and have nozzle openings 54 which dischargethe liquid product outwardly in a sprayv as the arms rotate. These armsextend through a deflector 55 which is atapered air conduit 56 which isin communication with the air-passage 31, as will-presently appear.

The deflector 55 is flared'at its lower end and has its side curved incross-section so as to defiect the air entering through the air conduit24 downwardly and outwardly, as will presently appear. I

The evaporator I6 is in the form of a cyclone separator having anenlarged cylindrical body portion 51, a lowerconical portion 58 and atop or upper, somewhat conical, portion 59. Theupper portion 59 has adepending downwardly tapered portion or extension 6| extendingabout thespindle 49 which is in the axis of the evaporator. The lower ends of thetapered portion 6| is curved downwardly and outwardly as at 62 to formwiththe curved'portion of the member 55 a passagefor directing the airdownwardly and outwardly within the evaporator across the nozzles 54. Y

The conduit 24 extendsfrom the dehydrator l1 through the heater 25 to apoint above the evaporator IB and terminates in a snail 63 above thedownwardly extending portion 6| in order that air passing through theconduit 24 and through 'the snail 63 will begiven a rotary movement sothat it will enter the evaporator in a rotating spiral form. Athermometer 66 is provided for indicating the temperature of the air inthe lower portion of the evaporator.

Suitable means are provided for withdrawing the air axially from theevaporator. In the form of the construction shown, the spray head 48 isso constructed that it forms an exhaust fan for this purpose. As showninFig. 6, the arms 53 are made in the form of fan blades so that theywill exhaust the air from the evaporator and discharge the same into thepassage 31.

It will thus be seen that the liquid product,

after it has had part of its moisture removed in heater 25, aconsiderable portion ofthe moisture will be evaporated andthe airremoved from the evaporator will be conducted'over to the vacuum chamberI2 for heating the liquid product contained therein, as described above.The concentrate collected in the-bottom ofthe evaporator I6 is withdrawnthrough a conduit 64 by means of. the pump 65'. and is delivered to the'dessicator I1.

The dehydrator or desiccator I1 is similar in construction to theevaporator l6 and comprises an, upper cylindrical section 69, a lowertapered section 1| and an upper ordome-like section 12 which has anaxial opening" 13 therein. The dome section 12 has a dependingconicalmember '14 which tapers downwardly and is flared out- I wardly at itslower end as; at15. Theconduit 22 for conducting heatedair to' thedehydrator I is provided with a snail 16 whichis attached'to the uppersection 12 and extends about the opening 13 so that air passingalong'the conduit22 the spray head 48, from the pipe 40.

located directly beneath ina' spray into the head 8| extends spindle isadapted tobe rotated by a motor the arms 83.-

will be caused to rotate and move downwardly throughthe opening 13'.

Suitable. means are provided for conducting the air delivered by theconduit 22 from the dehydrating chamber ll axially'thereof. The conduit24 through which the air is exhausted is provided at its outer end witha downwardly extending tapered section ll which extends through thesnail l8 and terminates adjacent to the curved portion 15 of the.airtdeflector 1.4. Secured to.

of the conduit 24,

v axially of the opening 18, isa tapered shield I8 axially through theshield 18.

82 mounted above the spindle. The spray head 8| is similar to the sprayhead 48 jandis pro- -vided with a plurality ofarms 88 that-are at- .-forcirculating the air 7 10 :chamber or pan l2. An air intake valve 88 is"and depending downwardly from, the upper wall and the-spindle .18cfaspray dicates the temperature of the said conduit. The fan 2| ismeadows mometer 828 indicates airinthe passage 81. 1 ditis used as theheating medium and itisf circulated in a closed system. The mechanismcharges the air'lnto the conduit 22 and,causee tachedto the spindle 19and have longitudinal liquid product passing along the pipe 64 from thepassages therethrough' in communication with an axial passage in thespindle 19 so that the evaporator IE will pass downwardly through thespindle I9 and be discharged in a spray through The arms 83 passoutwardly through a deflector 18 which has its outer surface curveddownwardly and outwardly as shown at 8,4 for directing air entering fromthe conduit 22 outwardly across the nozzles for dehydrating the liquidproduct discharged by said nozzles. In order to exhaust the air from thedehydrator, the arms 88 are in the form of fan blades as shown at 53 inFig. 6. 1 4 Since the spray head arrangement is substantially the sameas that shown in Fig. in, it is not thought necessary to further scribethe same. v The fan blades or arms 83 exhaust'the air the chamber throuillustrate or. de-

from the dehydrator l1 and discharge the same upwardly throughthetapered member 11 into I the conduit 24. The air entering through the iconduit 22 is of suchtemperature that the pare ticles of the liquidproduct are dehydrated and due to the centrifugal action of themass'within the. dehydrator chamber, the air. is separated and its pathof movement will now be described. I 1 Starting with the fan 2|. the airhdrawn into the fan 2| through the air con uit -28 whichnil it!communication with the jacket of the provided in the'air conduit 20 foradmitting fresh air as occasion may-be required A barometer 84 thepressure ofthe and is operated by a motor 88. The fan diethe same toflow along the .conduit into the H of the heater and a baille III whichextends down from. the top .wall thereof in a'plane substantially midwaybetween the battles and II.

The chamber 81 is provided at one end'with aiuel feeding device|82pwhich supplies fuel such as oil or gass to the combustion chamberand the products of combustion are discharged from gh a pipe I03 -atopposite ends of the chamber.

' a heating chamber m is mounted abovethe combustion chamber andthisheatingchambercomprises the perforated heads J88 and I88. in

the perforations of which are'secu'red dues or tubes I01 heated by thegases of combustion.

The air from, the fan 2| passes through these from the dehydratedparticles and is withdrawn bythe fan 88 as described above.

In order to reduce turbulence in the lower portion of the dehydrator II,'a double cone-shaped member 85 is mounted therein so that the rotat ingair, as it descends, will rotate about the upper portion of the doublecone thereby throwing the solid particles out against the walls of thedehydrator which will slide down the inclination of these walls. Theseparticles will slide downwardly and be discharged by a power operatedvalve 88 into a passage 81 leading to a snail 88 of a. combined coolerand centrifugal air separator, l8. The valve 88 is of the usual poweroperated type and is adapted, to be oper ated by a suitable motor 89..The outer end of the passage 81 is closed by a valve 9| which is adaptedto be opened or partially opened to,

. introduce fresh air for cooling the product down to storagetemperature, which in the case of milk powder may be around 100 F.Thepowder may be removed through power operated valve 88 operated bymotor 88 which permits the powder to fall by gravity into the containerI88. This air is utilized for conveying the mixture of air and or heater23. The air passing around the snail I8 is given a rotary movement andpasses downtubes and is heated as it passes through the same.

- The air passing through the superheater is discharged into the outerend of the pipe 22 and into the snail I8. A thermometer I88, is providedin the coriduit section 22 for indicating the temperature of the airpassing from the furnace wardly through the opening?" across the nozzlesof the arms 83 for dehydrating the spray of the liquid productdischarged by those nozzles. The concave surface ofvthe shield ordeflector i8 directs-the air outwardly toward the peripherytofwth'edehydrator and the centrifugal movement of this column 01 air throws thedehydrated particles of the product outwardly against the interior wallof the dehydrator and these particles slide downwardly-into the lowerportion of .the dehydrator and are removed through the valvelli aspreviously described. Y

The incoming air. rotates in a. wide-spiral as indicated by the arrowsHi9 about the vertical axistof the dehydrator and this spiral graduallynarrows toward the lower portion of the dehydrator and rotating aboutthe upper section of the cone in a small spiral moves upwardly in aspiral of small diameter and is-exhausted adapted to remove any ofdehydrated material to the separator is and for cooling the-material. Athermometer 92 attached to the dehydrator I1. is employed for indicatingthe temperature of the air therein and a therby the fan formed by theheader 8| and is dis charged through the shield section 11 into thereturn conduit 24 through a filter in whichis thesolid particles carriedalong with the all.

The air, in dehydrating the liquid products, has its temperaturegreatlyreduced and before air is introduced into the evaporator I8 fortor l6.

' nozzles 54 ther tially the the heated air 'ly' into the evaporator v vspiral, it comes'in contact with. the finely divided -cles. the bottomof the evaporator and be removed by i concentrating the 1 liquidproduct; it is passed through the heater for increasing its tempera tureThe he'ater 25 is similar in construction to the heater 23 and comprisesthecombustion chamber H2 abovewhich is. located the'heating chamber H3as in the previous constructions.

particles of the liquid product discharged by the and evaporates aconsiderable por-' tion of the moisture, contained in these parti- Theconcentrated liquid will flow down to the pump as described above. Thetemperature of the air will be greatly reduced in the evaporator 16' dueto its imparting heat to the liquid particles in concentrating theliquid,

The air will be withdrawn by the header 48 which functionsas a'ian'andis dis'charged'into the air passage 31 at greatly reduced temperature'.This air passes along the. passage 31 into the jacket of the vacuumchamber or pan l2 and passes further describe the same.

it rotates, it passes downwardly among the tubes 33 heating the same ber12 for boiling the liquid for evaporating the fresh liquid product 'supvplied to the evaporatorfrom the container or reservoir 1 I. The air,after passing through the vacuum chamber. has its temperature stillfurreduced and mcisture'removed therefrom by condensation, It isdischarged into. the air conduit 20 which completes the circuit.

In order that the system shall operate econom-' ically, it is desirablethat the air be recirculated and the temperatures maintained in thedifferent parts of the system .besubstantially constant. It is alsonecessary, in order to operate efficiently,

that .there be a substantially constant relationbetween the amount ofliquid treated and the temperature ofthe airjin the various parts. of.

the system in treating any particular'product.

It has been 'found that the following, .which is givenby way of exampleonly, gives satisfactory results for dehydrating or desiccating skimmilk.

In a plant having acapacity of fifteen pounds of milk powder per minuteand in which the evaporator chamber is probably fifteen feet .in-greatest:diameter and ten feethigh and the dehydrator chamber isprobably seventeen .feet in greatest diameter and probably eighteen feethigh. the following operating conditions were observed: l I g i The airenters the fan 2| at substantially 125 1 F; and 8500 cubic feet ofairper minute is passed through the fan. The air passes from thesuperheater at a temperatureof- 400.F-. and afterit passes through thedehydrator l1. into the-"conduit 24, its temperature is around-200 F.While in'the dehydrator, it has evaporated about thirty pounds of waterinproducing fifteen pounds of 6 powder. With that additional amount rmoisture in sucha volume of air,th'e saturation point of the air wouldbe around 140? so-that the air that is beingdischarged at 200' is abovethe saturation point. In passing through the superof the liquid at panto. around 130 .62.5 lbs.

amount of water from the milk, about 92.5 lbs.

I for heater 25, the temperature of the air is raised to 540'F.and isdischarged into the evaporating chamber I6 at that temperature. In theevaporating chamber, somewhere about 62.5 lbs. of water is evaporatedper minute. The air leaving the evaporator chamber isaround .160" F. andis saturated at that temperature. This saturated air passes into thevacuum pan or chainproduct introduced therein from the supply reservoir.A partial vacuum of around 27.5 inches is maintained in this vacuumchamber which results in a boiling around F. with a consequentcondensation of the moisture from the air. This absorption of heat bythe liquid reduces the temperature of the air passing through the vacuumF. with a consequent condensation of the moisture therein and the freshair introduced through the valve 93 will further reduce the'temperatureto around F. The amount of liquid suppied to the vacuum chamber or pan,is around 170 lbs. skimmed milk per minute and the amount of moistureevaporated, from this milk in the vacuum chamber is around per minute.In evaporating this of moisture is condensed and removed from this airthus reducing its temperature 'to around While the above data is givenin more or less detail, it is understood that the same is by way ofexample only and that the invention may vary within wide limits and thatthe scope of the invention is not to be limited beyond the terms of theclaims appended hereto.

It is thought from the foregoing, taken in connection with theaccompanying drawings, that the constructionand operation of my devicewill be apparent to those skilled in the art that changes in size,shape. proportion and details may be made without departing from thespirit and scope of the appended claims.

, I claim as my invention:

1. An apparatus for dehydrating milk and other -liquid productscomprising a desiccating chamber, an evaporating chamber, a vacuum panhaving heat exchange surfaces, a conduit for conducting air fromthe-vacuum pan to said'desiccating chamber, a second conduit forconducting air from said desiccator chambe'n'a passage for conductingair from said evaporating chamber to said vacuum pan and across saidheat exchange surfaces, heating means heating the air flowing in saidconduits, throughsaidchambers and across said heat exchange surfaces,-means fordischarging said air into said chambers in a rotary movement,means causing said product to pass through said pan and'chambers in adirection counter to the movement of the air through the same, means forspraying the product into said airwithin said '2. In an apparatus fordesiccating liquid products, a plurality 'of centrifugal air,separators,

means for circulatinga stream of air through said separators inv apredetermined order. in series, means for conducting a liquid product tosaid separatorsand for spraying said product into said separatorsinseries in the reverse order, means for heating the air to apredetermined high temperature just prior .to its introductioninto'oneof said separators fordesiccatin'g the product, means forheating theair discharged from said one separator to a temperature farto said evaporating its introductioninto another of said separators forremoving moisture from said sprayed product for concentrating theproduct, and means for preheating said product and removing moisturefrom said air preparatory to reusing thetair in the apparatus, saidlast-named meanscomprlsing a vacuum chamber throughwhich the airdischarged from said last-named separator is conducted, a reservoir forthe fresh liquid product, and means for conducting said fresh liquidproduct.to saidvacuum chamber from said reservoir and for conducting thesame from said reservoir to said second-named means.

3. In a system of dehydrating a liquidrproduct, a vacuum chamber in theform of a heat exchanger, an enlarged evaporating chamber, a

uid product first to to said evaporating said vacuum chamber, thenchamber and then to said decentrating said downwardly moving spiral onlyof said medium in said evaporating chamber for still further conproductand then conducting the liquidconcentrate from said evaporating chamberto said dehydrating chamber and spraying the same into the downwardlymoving spiral only of said drying medium in said dehydrating materialchamber, and finally removing the desiccated from said dehydratingchamber. ,5. Almethod of desiccating a liquid product in a continuousoperation which comprises circulating the same stream oi aircontinuously in a closed circuit through a-third, a second and a firstspace in series in the order named, concentrating a liquid product byfirst bringing the same into heat exchange relation with saiddehydrating chamber, means for conveying a liqhydrating chamber, arotary spray -for said evapl spraying said liquid product in saidevaporator and dehydrator, means for circulating the same air in aclosed circuit through said chambers without replenishing the airsupply. first to said vacuum chamber and then to said dehydratingchamber and then to said evaporating chamber,

means for heating the air during its passage between the evaporating anddehydrating chambers to a predetermined temperature, means for heatingthe air in its passage from the dehydrating chamber to the evaporatingchamber to a temperature above said predetermined temperature, means fordischars'ing said air across said sprays for evaporating moisture fromthe sprayed particles, and means for conducting said air through saidvacuum chamber in heat exchange relation to the fresh liquid uumchamber. e I

4. A method of concentrating and deslceating a liquid product in agaseous drying medium moving in a closed circuit which comprises passingall product in said vac-' stream of air in said first space while saidproduct is under subatmospheric pressure, then spraying the concentrateinto said stream of air within said second space, then spraying theconcentrate' from the second space into the stream of air in said thirdspace, causing said stream of air to movev spirally within said thirdand then said second spaceat high velocity, and heating said stream ofair just prior to each spraying process, the heating of said air beingmuch greater immediately prior to the spraying operation in the e thespraying operation in the third space. a

6. A method of evaporating and dehydrating -a liquid product whichcomprises heating a current of air to a temperature around 400 F.,causing the same to flow in a spiral form in a closed dehydratingchamber, conducting the air from said chamber, heating the same toaround 540' F.

and discharging the heated air into an evaporatof said medium through aheater, then causing the same to. move spirallydownwardly into andupwardly out of a dehydrating chamber, again heating said medium abovethat of the flrst heating and causing the same to flow spirallydownwardly into and upwardly out of an evaporating chamber, thenconducting all of said medium discharged from said but to a hightemperature ing chamber, causing the air to rotate in said evaporatingchamber, conducting said air from the evaporating chamber through a heatexchanger chamber for reducing the temperature and moisture contentthereof, recycling the air through said dehydrating chamber, saidevapcrating chamber and through said heat exchanger chamber, in series,in the order named, causing a liquid product to ilow through said heatexchanger chamber in heat exchange relation with said air passingtherethrough for concentration, conducting the concentrate of saidproduct from said last-named chamber to said evaporating chamber andspraying the same into the spirally moving air there n. conducting theconcentrate to said dehydrating chamber and spraying the same into thespirally moving air therea in, and finally collecting the dehydratedmate- Joann: u. HALL.

